"The acquisition will lead to only a small increase in Xstrata's market share in the supply of refined copper, gold and silver markets on a worldwide basis. Likewise, the acquisition would lead to only a small increase in market share in respect of gold and silver in Australia.

"In relation to refined copper, the ACCC has formed the view that while the proposed acquisition would result in a significant increase in market share in Australia, Xstrata will continue to face competition from a number of multinational copper refining and production companies".

The ACCC also noted Xstrata's existing relationship with Glencore International AG but did not see that it, combined with Xstrata's proposed acquisition of WMC, would result in a substantial lessening of competition.

The global merger remains conditional on approval from a number of international antitrust authorities which have not yet completed their evaluation.

The acquisition also remains subject to WMC shareholder acceptance of Xstrata's offer.